The trial of a preacher accused in the 1964 murders of three U.S. civil rights workers has been delayed indefinitely, after the accused man was taken from the Mississippi courtroom on a stretcher.

Video footage shows Edgar Ray Killen, 80, conscious and sitting upright as he was taken from the court. His lawyer said he was suffering from high blood pressure.

Mr. Killen is accused of instigating the 1964 slaying of three young men, who were in Mississippi to help register African American voters.

Mr. Killen's attorney says his client, a former member of the white supremacist group the Ku Klux Klan, had recruited people to beat the three civil rights workers but did not kill them. Mr. Killen has maintained his innocence.

He was tried in 1967 on federal charges of violating the victims' civil rights, but an all-white jury deadlocked one vote shy of conviction.